The present invention relates to xanthene polyesters and polyamides and copolymers thereof, and esterification, transesterification and amidation methods which are used in the synthesis of such xanthene containing polymers and copolymers. There are employed in the synthesis of such xanthene containing polymers, xanthene containing dicarboxylic acids, and derivatives thereof, such as the corresponding acid halides and esters.
In Pfeifer et al., U.S. Pat. No. 4,714,669, there are provided radiation sensitive thioxanthone and xanthone containing polycondensates. These polymers are prepared by effecting reaction between a diphenyl thioxanthone dicarboxylate, such as diphenyl thioxanthone-10,10-dioxide-2,6-dicarboxylate, or a xanthone dicarboxylate, such as diphenyl xanthone-3,6-dicarboxylate, and an alkylene diol. Pfeifer et al. report, that some of the thioxanthone and xanthone polycondensates are thermoplastic and high melting. However, due to the radiation sensitivity of the thioxanthone and xanthone structures, the utility of these materials is often restricted to applications in which photolability is advantageous.
It would be desirable therefore to provide high performance xanthene containing thermoplastics, such as xanthene polyesters, polyamides, and copolymers thereof which can be applied in a variety of applications, for example high performance films, fibers, injected molded or extruded parts, tubing, wire coatings, automotive applications such as connectors, computer housings, and packaging film.
As shown in copending application Ser. No. 08/218,397, polyalkylated xanthenes can be made by transforming a bisphenol A (BPA) containing material, such as a BPA tar, or BPA, with an alkylphenol, such as m or p cresol, or a mixture thereof, or a dialkylphenol, such as 3,4-dimethylphenol, in the presence of an acid catalyst. There is produced a nearly quantitative yield of phenol and a satisfactory yield of a polyalkylated substituted 9,9-dimethylxanthene included within the formula, ##STR1## where R, R.sup.1, R.sup.2, and R.sup.3 are members selected from the group consisting of the same or different C.sub.(1-4) alkyl radicals and a mixture consisting of hydrogen and the same or different C.sub.(1-4) alkyl radicals. These xanthenes can be readily oxidized to xanthene carboxylic acids. Among these polyalkylated 9,9-dimethyl xanthenes, there are included dialkyl xanthenes which can be substituted with two C.sub.(1-4) alkyl radicals, which can be the same or different, and located in the 3,6 position, the 2,7 position, or the 2,6 or 3,7 position. These dialkyl 9,9-dimethylxanthenes can be oxidized to xanthene dicarboxylic acids selected from the group consisting of, ##STR2##
The above xanthene dicarboxylic acids also can be converted to their corresponding acid halides and dialkyl esters, such as the 2,6 dimethyl ester, the 2,7 diethyl ester, the 2,6 dipropyl ester, or the corresponding diaryl esters, such as the 3,6 diphenyl ester, by standard procedures.